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11.
Rate constants have been measured (by laser induced fluorescence) for the quenching of metastable Ca(3P) by the ground states of Ca and Mg and by the inert gases. Rate constants for the metals were considerably larger than for the inert gases. The cross sections for the inert gases are well correlated by an orbiting model. 相似文献
12.
Calculations based on density functional theory (DFT) and Hartree-Fock configuration interaction (HF-CI) methodology have been carried out to investigate the rhodium-rhodium coupling in Rh(2)(CO)(2)(dppm)(2), 1 (dppm = Ph(2)PCH(2)PPh(2)) and in Rh(2)(&mgr;-CO)(CO)(2)(dppm)(2), 2. DFT geometries, obtained with the Dgauss program, are in good agreement with those determined from X-ray, but HF geometries, calculated using the same basis sets, yield bond distances systematically too long. Calculations indicate that the rhodium atoms in 1 are linked by a single bond. The insertion of a semibridging carbonyl between the two metal atoms leads to a shortening of the rhodium-rhodium distance and also to a noticeable weakening of the metal-metal interaction. Both effects, and also the stabilization of the HOMO of 2, are related to an observed change from square planar to tetrahedral of the ligand environment of the Rh atom proximal to the inserted CO. Both MO analysis and bond characterization from the topology of the charge density confirm the existence of a bonding interaction between the semibridging carbonyl and the distal rhodium atom. The electronic structures of the dicationic complex [Rh(2)(CO)(3)(dppm)(2)](2+) and of the A-frame-like, isoelectronic system Rh(2)Br(2)(&mgr;-CO) (dppm)(2) are also discussed. The electron deformation density is derived from 2 by means of several methodological approaches, namely, HF, HF-CI, DFT, and DFT + gradient corrections. The HF deformation density obtained in the plane containing the metals and the three CO ligands is discussed, as well as the "correlation density" obtained from the difference maps DFT - HF and CI - HF. 相似文献
13.
BACKGROUND: Although neutrophilic granulocytes clearly contribute to cartilage degradation in rheumatic diseases, it is unclear if reactive oxygen species (ROS) or proteolytic enzymes are the most important components in cartilage degradation and how they interact. RESULTS: Neutrophils were stimulated by chemicals conferring a different degree of ROS formation and enzyme release. Supernatants of neutrophils were incubated with thin slices of pig articular cartilage. Supernatants of cartilage were assayed by NMR spectroscopy, MALDI-TOF mass spectrometry and relevant biochemical methods. Stimulation conditions of neutrophils correlated well with the extent of cartilage degradation. Due to the release of different enzymes, cartilage degradation could be best monitored by NMR since mainly low-mass degradation products were formed. Astonishingly, the suppression of the formation of ROS resulted in decreased cartilage degradation. CONCLUSION: ROS formed by neutrophils are not directly involved in cartilage degradation but influence the activity of proteolytic enzymes, which are the main effectors of cartilage degradation. 相似文献
14.
This work describes the influence of silica fillers on the thermomechanical properties of diglycidyl ether of bisphenol A/triethylenetetramine (DGEBA/TETA) epoxy resins during ageing under electron beam irradiation. Whatever be the silica filler (pure micrometric ground and spherical silicas, nanometric silicas and coupling agent treated silicas), the glass transition temperature of the epoxy resins decreases with increasing irradiation dose, meaning that the main effect of the irradiation is chain scission. No influence of the silica fillers has been detected from the changes in the glass transition temperature with the increase in the irradiation dose. The disappearance of the cooperativity of the γ relaxation, the decrease of the α relaxation and the decrease of the elastic modulus at the rubbery plateau observed by dynamic mechanical analyses involve a decrease in the crosslink density of the epoxy resins. The occurrence of chemical reactions between the epoxy resin and the silica surface at high irradiation doses has been shown. Moreover, we show evidence that chemical reactions between the epoxy resin and the silica surface occur at high irradiation dose. 相似文献
15.
H. Mardanpour H. R. Amir-Ahmadi R. Benard A. Biegun M. Eslami-Kalantari N. Kalantar-Nayestanaki M. Kiš St. Kistryn A. Kozela H. Kuboki Y. Maeda M. Mahjour-Shafiei J. G. Messchendorp K. Miki S. Noji A. Ramazani-Moghaddam-Arani H. Sakai M. Sasano K. Sekiguchi E. Stephan R. Sworst Y. Takahashi K. Yako 《Few-Body Systems》2008,44(1-4):49-52
A systematic study of three-nucleon force (3NF) effects in break-up reactions has been carried out at KVI at several energies. In this article, the p + d → p + p + n reaction with a polarized-proton beam of 190?MeV will be discussed. The experiment was performed by exploiting a new detector called BINA. Some results for high-precision vector analyzing powers and differential cross sections are presented and compared with state-of-the-art Faddeev calculations with or without 3NF. 相似文献
16.
Emission from diatomic LiCa molecules was obtained upon pumping a mixture of Li and Ca vapors with an Ar+ion laser. The excited LiCa molecules were formed via reactions of excited Li2 dimers with Ca atoms. The LiCa emission was analyzed spectroscopically and found to be in good agreement with a synthetic spectrum derived from ab initio calculations of the LiCa potential-energy curves 相似文献
17.
Attachment line boundary layer transition on swept cylinders is studied in a low enthalpy hypersonic wind tunnel at M
∞=7.14. Sweep angles of 60° and 70° are used and transition is detected by means of heat flux measurements. The influence on
attachment line transition of single 2D-roughness elements, in the form of tripwires or slots, as well as 3D obstacles is
determined and the results are analyzed with respect to Poll’s criterion.
Received: 16 January 1996 / Accepted: 12 July 1996 相似文献
18.
Mg atoms were vaporized into a fast flowing Ar carrier stream and then excited by an ac discharge. Downstream of the discharge in the afterglow region metastable Mg (3P) atoms were reacted with vaporized metals. The resultant chemiluminescence consisted of metal atom resonance lines and continuous emission bands of the molecule KMg. 相似文献
19.
Yvonnick Loidreau Carole Dubouilh‐Benard Pascal Marchand Marie‐Renée Nourrisson Muriel Duflos Catherine Buquet Cécile Corbière Thierry Besson 《Journal of heterocyclic chemistry》2013,50(5):1187-1197
A useful and rapid access to libraries of N‐arylbenzo[b]furo[3,2‐d]pyrimidin‐4‐amines ( 1 ) and their novel benzo[b]thieno[3,2‐d]pyrimidin‐4‐amine analogues ( 2 ) was investigated for the first time. Title compounds were obtained via microwave‐accelerated condensation and Dimroth rearrangement of suitable anilines with N′‐(2‐cyanaryl)‐N,N‐dimethylformimidamides obtained by reaction of benzo[b]furane and benzo[b]thiophene precursors with N,N‐dimethylformamide dimethyl acetal. This work also demonstrates that well‐controlled parameters offer comfortable use of microwave technology and are both safe and beneficial to the environment. Some products obtained in this article exhibit interesting in vitro antiproliferative effects. 相似文献
20.
V. Hanemaayer F. Benard K. R. Buckley J. Klug M. Kovacs C. Leon T. J. Ruth P. Schaffer S. K. Zeisler 《Journal of Radioanalytical and Nuclear Chemistry》2014,299(2):1007-1011
Recent disruptions in the molybdenum-technetium generator supply chain prompted a review of non-reactor based production methods for both 99Mo and 99mTc. Small medical cyclotrons (E p ~ 16–24 MeV) are capable of producing Curie quantities of 99mTc from isotopically enriched 100Mo using the 100Mo(p,2n)99mTc reaction. Unlike most other metallic target materials for routine production of medical radioisotopes, molybdenum cannot be deposited by reductive electroplating from aqueous salt solutions. To overcome this issue, we developed a new process for solid molybdenum targets based on the electrophoretic deposition of fine 100Mo powder onto a tantalum plate, followed by high temperature sintering. The targets obtained were mechanically robust and thermally stable when irradiated with protons at high power density. 相似文献